Known bearing assemblies may include a housing element or a hub element that has at least one opening for receiving first and second bearing rings such that the second bearing ring is movable relative to the first bearing ring. These may be used, for example, as wheel hub bearing assemblies in motor vehicles. In such assemblies, the bearing outer ring is usually press fit in the at least one opening on the hub element. The bearing rings must be strong enough to withstand the forces to which they are subjected and are therefore generally made mostly of steel, in particular of rolling-element bearing steel (e.g., 100Cr6). In order to reduce weight, a lighter material, such as aluminum, is often used to form the hub element or housing element.
The light weight of aluminum wheel hubs makes them desirable for wheel-bearing arrangements. A disadvantage of aluminum wheel hubs, however, is that aluminum has a substantially greater coefficient of thermal expansion as compared to that of steel. This means that it is difficult to design the connection or interface between steel parts and aluminum parts for all relevant temperature ranges. The different degrees of expansion may prove particularly troublesome at the press-fit junction between the hub element and the bearing outer ring. At high temperatures the fit between these elements can loosen, since the aluminum hub will expand more than the steel bearing ring. This may allow the bearing outer ring to shift or rotate in the hub, and such movement can damage the hub and/or the bearing.
On the other hand, at low temperatures the aluminum hub strongly constricts the outer ring and may cause high contact stresses. This may cause the hub to crack or may deform the bearing ring, in particular on the raceway.
It was therefore proposed in DE 10 2012 211 261 (family member of U.S. Pat. No. 8,961,028) to provide a specific design for a bearing assembly with a hub element or housing element and a rolling-element bearing outer ring press-fit in a receiving bore. In order to ensure a proper fit of the bearing ring at all operating temperatures, even with the use of different materials for the hub element or housing element and the bearing ring, the designs of the receiving bore and of the outer circumference of the outer ring are configured in a particular manner. Specifically, they are configured such that the radial press-fit between receiving bore and the outer ring is smaller in the region of the raceway than in the region outside the raceway. This can be achieved, for example, by the varying the diameter of the receiving bore or of the outer ring over its axial length.
However, a disadvantage of this conventional approach is that forming the axial extensions of the receiving bore or outer ring with varying diameters is very expensive, and in addition each element must be individually manufactured. Such bearing assemblies are thus very cost-intensive.